Autunite
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Mineral NameAutunite
Chemical FormulaCa(UO₂)₂(PO₄)₂·10-12H₂O
Mohs Hardness2
Crystal Systemtetragonal
Lustervitreous
Streak Colorpale yellow
Cleavageperfect on {001}, distinct on {100} and {010}
Fractureuneven
Specific Gravity3.1
Colorsyellow-green, lemon-yellow
Transparencytransparent
Type LocalityQuarry near Streuberg, Bergen / Vogtland (Germany)
Mineral GroupPhosphates
Usescollector, minor uranium ore
Associated Mineralsuraninite, torbernite, quartz, feldspar
Rarityuncommon
Description
This specimen features a vibrant yellow-green aggregate of platy, micaceous autunite crystals, forming radiating clusters on a dark matrix with some lighter crystalline material.
Geological Context
Autunite is a secondary uranium mineral that forms in the oxidized zones of uranium-bearing ore deposits, often as an alteration product of primary uranium minerals like uraninite in granitic rocks or pegmatites.
